Design of a new foot structure based on the mast-type octahedral tensegrity structure

Abstract

• A foot structure was developed basing on mast-type octahedral tensegrity structure. • To obtain the ability of rigid-flexible switching by adding ratchet structure. • Better self-adaptability, self-stability, self-recovery and stable support capacity. • The foot structure can satisfy the human ankle joint reachable workspace . • The foot structure can enhance adaptability in walking. Foot performance plays an important role in the walking-style robot walking in complex ground. This paper proposes a new foot structure based on the mast-type octahedral tensegrity structure with the flexibility, self-stability and self-adaptability. First, the mast-type octahedral tensegrity structure is evolved, and the feasibility of the motion is verified by dynamic analysis, and the degrees of freedom of the structure are limited by adding cross-axis. Next, by adding a locking structure based on a ratchet structure, and it avoided the structural instability caused by excessive deformation of the tensegrity foot structure. Finally, the design of the new foot structure was completed and a physical prototype was fabricated to verify the function of the new foot structure through relevant experiments. The high symmetry of the mast-type octahedral tensegrity structure simplifies the stiffness matching of the elastic members of the tension foot mechanism. The locking structure based on the ratchet structure is used to realize the switching of the flexible adaptation function and the rigid support function of the tensegrity foot structure, thus avoiding the structural instability caused by excessive deformation of the tensegrity foot structure.